A series of neurophysical studies will be made of the central mechanisms of the larynx. The primate macaca mulatta will be employed as the experimental animal to determine cortical and subcortical areas in the motor control of the intrinsic laryngeal muscles. The cortical and subcortical areas of the brain will be explored and plotted by macrostimulation and microstimulation techniques, with confirmation of identified areas made by recordings of muscle contractions. Discrete lesions or injection of radioactive isotopes then will be made of the areas plotted to delineate, histologically, anatomical motor pathways. Findings will be correlated to normal functions and neuropathological entities of the laryngeal organ. Very little is known about the central mechanisms of the larynx, and the work have special significance for the neuronal processes underlying vocalization.